Optimization of gas input in aqueous two-phase flotation (ATPF) for enzyme purification

L. Jakob*, J. Singer, H. Nirschl, Karlsruhe Institute of Technology (KIT), Germany

The purification of industrial enzymes from complex biosuspensions represents a major challenge for the bioprocess. Many separation steps are necessary to capture the target protein from the fermentation broth and to increase the purity up to the final product. During downstream processing, various processes are used, such as centrifugation, filtration, precipitation, extraction or chromatography, so that losses and energy costs of the individual steps sum up and the purification costs for enzymes usually represent more than 50% of the production costs.

In protein extraction from complex biosuspensions, aqueous two-phase systems (ATPS) ensure mild conditions and high selectivity against the target protein. ATPS are formed when a polymer or a lower alcohol is dissolved in water with another polymer or salt above the critical concentrations (mixing gap). During extraction, impurities (cells, cell debris, media components, ...) remain in the heavy lower phase while the target protein diffuses into the upper, lighter phase.

The flotation of enzymes in aqueous two-phase systems (aqueous two-phase flotation, ATPF) combines the selectivity of the extraction with the high mass transfer of the flotation. By introducing gas bubbles into the two-phase system, proteins with their hydrophobic part attach themselves to the gas-liquid interface and are transported to the upper phase after the bubbles have risen (see Fig.1). This allows to perfom "Capture" and "Clean" in one step. The ATPF was described for the first time2 in 2009 and promises to be an efficient alternative to conventional purification processes of biotechnological products by eliminating several separation steps warranting mild conditions.

However, more research is needed to develop the new technology on its way to an industrial use. Especially the gas input in the two-phase system has to meet several demands.

Within the research project, ATPF will be fundamentally investigated for its application potential for the purification of industrial enzymes...

Session: L18 - Froth Flotation and Liquid/Gas Separation
Day: 24 October 2019
Time: 13:00 - 14:15 h

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